Mathematics
OpenStudy (anonymous):

Proving the (imaginary) teacher wrong! (geometry)

OpenStudy (anonymous):

OpenStudy (kropot72):

In the right angled triangle ADE use the theorem of Pythagorus to find ED.$ED ^{2}=13^{2}-12^{2}$

OpenStudy (kropot72):

When you find ED you know EF and can work out the length of AB

OpenStudy (anonymous):

OpenStudy (kropot72):

What did you get for the length AB?

OpenStudy (anonymous):

Here are the answers I am given. But based on what you have said: 12+3.6+12=27.6

OpenStudy (kropot72):

So you calculated ED to be 3.6. Did you calculate ED as per the equation I gave earlier?

OpenStudy (anonymous):

i messed up! my apologies. I must have done something wrong. I now realize that it should have been 17.7, not 3.6.

OpenStudy (kropot72):

No. ED is not 17.7$ED ^{2}=13^{2}-12^{2}=169-144=25$ $ED=\sqrt{25}$

OpenStudy (anonymous):

oh my goodness. I am not on my game today.

OpenStudy (kropot72):

Do you now understand what the correct choice should be?

OpenStudy (anonymous):

Yes I do. Thanks for the help.

OpenStudy (kropot72):

You're welcome. Good on you for perservering :)